(a) Field of the Invention
The present invention is related to a central positioning device for a labeling machine of heat shrinkable film, and more particularly, to one that deflects the heat shrinkable film label for its surface of the logo to precisely match the relative surface on the bottle as desired.
(b) Description of the Prior Art
In earlier time, text or pattern is directly printed on or a sticker is directly adhered to the surface of the bottle. Color performance is monotonous due to technical problem of color scheme in direct printing while the sticker fails to express the sense of quality. Thereafter, labels are made of film in closed loop to be inserted onto the bottle. Usually, the shrinkable film printed with text and pattern is wrapped around the bottle before being thermally treated to fasten the film on the bottle. However, the work efficiency for this production is less satisfactory since it takes to cut the flat film into the size desired and to prop open to wrap around the bottle by manual before being thermally treated into shape. Later, to solve the problem of deficiency in manual work, a heat shrinkable labeling machine is developed to replace the manual operation.
A pair of primary rollers and another pair of feeder rollers are essentially used in the automatic labeling machine of heat shrinkable film of the prior art to prop open the heat shrinkable film to be wrapped around the bottle by rolling to deliver the film and a conic cylinder, i.e., the central positioning device, is used to prop open the film and wrap it around the bottle.
To the mechanism of the central positioning device in the form of a conic cylinder, it has achieved the basic purpose of labeling on the general round bottles. However, when the labeling machine is used on square bottles, the following flaws are observed:
Whereas the heat shrinkable film is continuously printed and wound in the form of a roll, the tubular film is flattened into having two sides flushed against each other resulting in two folding marks that survive even after the film is prop opened by the conic cylinder of the central positioning device. The diameter of the heat shrinkable film before being thermally treated is slightly greater than the outer diameter of the bottle (the square bottle in this case) to facilitate to be inserted onto the bottle. Once the bottle is inserted with the film, the film that contacts the bottle becomes vulnerable to get slacken or displaced, and particularly so when the folding marks fall upon the flat surface of the square bottle. Whereas text and pattern printed on the heat shrinkable film are already positioned in terms of the front, the rear and both sides of the bottle, any displacement of the heat shrinkable film will result in misplaced text and pattern to lose the appearance as desired.